Inventário sobre os padrões de lançamento de efluentes e reúso de águas e análise de eficiência e confiabilidade de um efluente industrial

Abstract

The industry is a high potable water consumer due to its own processes demand of this source. Most industries have a Sewage Treatment Plant, in which the effluents are released in water bodies. However, the sewage could be reutilized by the industry, aiming water economy and reduction of the impacts of effluent disposal. This study aimed to develop an inventory of sewage treatment standards and wastewater disposal and reuse, to set restrictive levels and to conduct an efficiency and reliability analysis in order to assess compliance with SEMACE 154/2002, upon evaluation of effluent coming from a dairy industry, with the possibility of reuse in irrigation. Evaluation of physicochemical quality and microbiological data coming from the STP together with reliability analysis was conducted in parallel with the inventory of wastewater disposal, in which restrictive levels based on parameters adopted in 17 Brazilian states were established, in comparison with federal law. The analysis attempted to verify the accordance with the current legislation under less restrictive standards. The sewage from the STP was poorly in compliance with the legislation established by SEMACE nº 154/02 regarding COD, TSS, NH3 and E coli levels. The inventory of Wastewater Disposal Standards and the restrictive levels demonstrated many limits set by SEMACE nº 154/02 are classified as too restrictive or restrictive, which becomes a restraint in accomplishing compliance with the established standards. By using less strict limits adopted in other Brazilian states, such as RS, PE, RJ and MG, it was clear that parameters with low level of compliance, COD and Ammonia, achieved an expressive positive change, becoming compliant with the set target. However, even with a less restrictive concentration, the TSS kept non-compliant with the target due to high concentrations present in the sewage of stabilization pond systems. Also, some other parameters did not follow recommendations usually adopted during reuse in irrigation, as pH, TSS, TSD, Ammonia, Chlorides, Sodium and E. coli. Thus, it is not recommended to use the treated sewage in the irrigation process due to the high risk in soil salinization and the lack of legal support. Ultimately, the importance of a revision of the current criteria adopted on wastewater disposal in water bodies in the state of Ceara, as well as the establishment of federal and state legislations that set up reuse standards to be followed in different activities are the conclusions resulted from the evaluation here presented